diff --git a/crates/ailang-core/src/workspace.rs b/crates/ailang-core/src/workspace.rs
index 061295d..cf4484b 100644
--- a/crates/ailang-core/src/workspace.rs
+++ b/crates/ailang-core/src/workspace.rs
@@ -2557,4 +2557,54 @@ mod tests {
             other => panic!("expected QualifiedClassName, got {other:?}"),
         }
     }
+
+    /// ct.1: on-disk fixture for `BareCrossModuleTypeRef`. Bare
+    /// `Ordering` Term::Ctor with no imports; the validator catches it
+    /// after prelude injection (so the candidate list contains
+    /// `prelude.Ordering`).
+    #[test]
+    fn ct1_fixture_bare_xmod_rejected() {
+        let entry = examples_dir().join("test_ct1_bare_xmod_rejected.ail.json");
+        let err = load_workspace(&entry).expect_err("must reject bare Ordering");
+        match err {
+            WorkspaceLoadError::BareCrossModuleTypeRef { module, name, candidates } => {
+                assert_eq!(module, "test_ct1_bare_xmod_rejected");
+                assert_eq!(name, "Ordering");
+                assert_eq!(candidates, vec!["prelude.Ordering".to_string()]);
+            }
+            other => panic!("expected BareCrossModuleTypeRef, got {other:?}"),
+        }
+    }
+
+    /// ct.1: on-disk fixture for `BadCrossModuleTypeRef`. Qualified
+    /// `Mystery.Type` with `Mystery` not a known module.
+    #[test]
+    fn ct1_fixture_bad_qualifier() {
+        let entry = examples_dir().join("test_ct1_bad_qualifier.ail.json");
+        let err = load_workspace(&entry).expect_err("must reject Mystery.Type");
+        match err {
+            WorkspaceLoadError::BadCrossModuleTypeRef { module, name } => {
+                assert_eq!(module, "test_ct1_bad_qualifier");
+                assert_eq!(name, "Mystery.Type");
+            }
+            other => panic!("expected BadCrossModuleTypeRef, got {other:?}"),
+        }
+    }
+
+    /// ct.1: on-disk fixture for `QualifiedClassName`. Qualified
+    /// `prelude.Eq` in an `InstanceDef.class` field — the schema
+    /// rejects this so half-migrated files cannot silently load.
+    #[test]
+    fn ct1_fixture_qualified_class_rejected() {
+        let entry = examples_dir().join("test_ct1_qualified_class_rejected.ail.json");
+        let err = load_workspace(&entry).expect_err("must reject prelude.Eq");
+        match err {
+            WorkspaceLoadError::QualifiedClassName { module, name, field } => {
+                assert_eq!(module, "test_ct1_qualified_class_rejected");
+                assert_eq!(name, "prelude.Eq");
+                assert_eq!(field, "InstanceDef.class");
+            }
+            other => panic!("expected QualifiedClassName, got {other:?}"),
+        }
+    }
 }
diff --git a/examples/test_ct1_bad_qualifier.ail.json b/examples/test_ct1_bad_qualifier.ail.json
new file mode 100644
index 0000000..a02d4a1
--- /dev/null
+++ b/examples/test_ct1_bad_qualifier.ail.json
@@ -0,0 +1,19 @@
+{
+  "schema": "ailang/v0",
+  "name": "test_ct1_bad_qualifier",
+  "imports": [],
+  "defs": [
+    {
+      "kind": "fn",
+      "name": "f",
+      "type": {
+        "k": "fn",
+        "params": [],
+        "ret": { "k": "con", "name": "Mystery.Type" },
+        "effects": []
+      },
+      "params": [],
+      "body": { "t": "lit", "lit": { "kind": "unit" } }
+    }
+  ]
+}
diff --git a/examples/test_ct1_bare_xmod_rejected.ail.json b/examples/test_ct1_bare_xmod_rejected.ail.json
new file mode 100644
index 0000000..ea7b500
--- /dev/null
+++ b/examples/test_ct1_bare_xmod_rejected.ail.json
@@ -0,0 +1,24 @@
+{
+  "schema": "ailang/v0",
+  "name": "test_ct1_bare_xmod_rejected",
+  "imports": [],
+  "defs": [
+    {
+      "kind": "fn",
+      "name": "main",
+      "type": {
+        "k": "fn",
+        "params": [],
+        "ret": { "k": "con", "name": "Unit" },
+        "effects": ["IO"]
+      },
+      "params": [],
+      "body": {
+        "t": "ctor",
+        "type": "Ordering",
+        "ctor": "LT",
+        "args": []
+      }
+    }
+  ]
+}
diff --git a/examples/test_ct1_qualified_class_rejected.ail.json b/examples/test_ct1_qualified_class_rejected.ail.json
new file mode 100644
index 0000000..929f769
--- /dev/null
+++ b/examples/test_ct1_qualified_class_rejected.ail.json
@@ -0,0 +1,13 @@
+{
+  "schema": "ailang/v0",
+  "name": "test_ct1_qualified_class_rejected",
+  "imports": [],
+  "defs": [
+    {
+      "kind": "instance",
+      "class": "prelude.Eq",
+      "type": { "k": "con", "name": "Int" },
+      "methods": []
+    }
+  ]
+}